Motor operated hand tool for setting fasteners



Jul 3, 1962 GEORGE s. WING 3,041,902

MOTOR OPERATED HAND TOOL FOR SETTING FASTENERS Original Filed May 27, 1957 FIG./

FIG.2. 1 16.55.

INVENTOR- 6 1966 S. w/M e ATTORNE S United States Patent 4- Claims. (Cl. 81-56) This invention relates to a tool for setting blind fasteners of the type in which a collar is threaded onto a pm.

This application is a division of applicants co-pending application, Serial No. 661,874, filed May 27, 1957, entitled Fastener and Tool for Setting the Same.

An object of this invention is to provide a tool for setting fasteners generally, and in particular for setting blind fasteners of the type in which a threaded collar is tightened down onto a threaded pin, and wherein, after a predetermined torque has been applied between the two parts of the fastener, a section of one of said parts fractures, thereby limiting the torque which can be applied to the fastener and indicating that a sufficient torque has been applied.

An objection to previously known tools for setting blind fasteners of this class has resided in their transmitting torque forces to the operator, instead of keeping the torques in a closed system isolated from him. For example, many counter-rotative wrenches for this purpose have had a portion of the counter-rotative mechanism fixed to structure which is held by the operator so that the operators reaction to the torque, exerted by twisting on the structure, enters into the amount of torque applied to the fastener, and the rate at which it is applied. This is undesirable for two reasons. First, it makes variable the torque which is actually exerted on the fastener by the tool and the rate it is applied, which should both be constant from fastener to fastener; and second, when the fastener yields suddenly, the tool may give a jerk which is uncomfortable or bothersome to the operator. The tool according to this invention confines the torque to a closed system not felt by the operator, so that the tool is very sensitive to the torque actually applied to the fastener, and the operator cannot vary it at all.

A tool according to this invention comprises a housing with an inner cavity and a ring gear attached to the housing in said cavity. The tool also includes a wrench for engaging the wrench engaging surfaces on the pin, a spider member, a central drive gear member, and a planetary gear journaled only to said spider meshing with the drive gear and the said ring gear. A drive shaft turns the spider or the drive gear, and the other of said spider or drive gear turns the aforesaid wrench. A socket is attached to the housing, and as a consequence of the operation of the planetary gear train, the wrench and socket are counter-rotated. When either the wrench or the socket is stopped, then the other can turn so as to tighten the collar on to the pin, the collar being engaged in the socket. When suliicient torque is exerted on the fastener, the section of the pin having the wrench engaging surfaces of the fastener breaks away at the aforesaid groove, leaving the collar torqued on the pin at the predetermined torque value.

The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings, in which:

FIG. 1 is a side elevation largely in cross-section of a tool according to this invention; FIG. 2 is a cross-section taken at line 22 of FIG. 1; FIG. 3 is a cross-section taken at line 3-3 of FIG. 1; FIG. 4 is a fragmentary cross-section taken at line 44 of FIG. 2; and FIG. 5 is a fragmentary isometric view showing a portion of the tool.

FIG. 1 shows the presently preferred embodiment of the invention. Its principal use is for setting a fastener comprising a pin and a collar 21 which is shown with the pin inserted through registering holes 36 and 37 in plates 38 and 39, respectively. These plates are to be joined by this fastener. The collar is first threaded onto the pin. The pin has a wrench engaging section 19 and there is preferably, but not necessarily, a groove between this section and the threaded shank of the pin adapted to torque off after a given torque has been exerted between the collar and the wrench engaging section. This tool is particularly useful in setting fasteners which do include a frangible section of this type, but this is not a limitation on the general utility of the tool. The wrench engaging section 19 of the pin is then inserted into a similarly shaped recess having fastenerengaging surfaces 40 in the shape of a hexagonal prism in the end of a wrench 41. The wrench is concentric around a central axis of rotation 42 of the tool. The wrench is rotatably journaled in a bearing 43 which bearing is mounted in a housing 44. The housing may conveniently be made of two housing portions 45, 46 which disposed to the side of the central axis 42, in engagement with both the central drive gear 52 and with the ring gear 48. The central drive gear has key slot 53 therein (see FIG. 6) into which a drive shaft 54 is inserted. The drive shaft has a tongue section 55 which enters and engages the aforesaid slot 53. The drive shaft 54 is: rotatably journaled in a thrust bearing 56 that is mounted in the housing, and the spider is further supported by another bearing 57 also mounted in the housing.

The drive shaft 54 passes through a drive shaft passage 54a in the spider and projects from the housing, where it may be held by a chuck 58 mounted to a drill motor 59 or some other motive means for turning the drive shaft.

The housing has a tubular portion 60 projecting to the right in FIG. 5 which surrounds and is concentric with the wrench. Four slots 61 in this tubular portion receive studs 62. These studs protrude from a socket 63 and are slidable in the slots 61, whereby the socket itself is slidable within the tubular portion. A coil spring 64 is placed within the aforesaid tubular portion in opposition between F the housing and the socket so as to press the socket to the right as shown in FIG. 5.

The socket is provided with a collar receiving recess 65 having surfaces suitable for engagement with the wrench engaging section 22 of the collar.

The wrench, socket, cage, drive shaft and drive gear are all concentric on axis 42.

The operation of the tool will now be described.

Initially, the holes 36 and 37 in bodies 38 and 39 to be joined are placed in registration in the manner shown in FIG. 1. The pin is passed through the registering holes with the head 12 pressing against one of said bodies and the threads 15 on the pin projecting out of the hole on the other of said bodies. The collar is then loosely threaded on to the pin. Thereafter the socket 63 is placed in engagement with the wrench engaging section 22 on the collar, and the wrench engaging section I? of the pin is inserted in the recess 40 in the wrench. Power is then applied to the motor and as will be evident from an examination of the drawings the wrench and the housing (and therefore the socket) will counter-rotate. It is i1nmaterial in this device whether the wrench or the socket actually rotates, so long as one of them does. In this device, it is possible for either to stand still while the other one rotates.

When the tool is first operated, there is a tendency for both the wrench and the socket to turn. However, there will ordinarily soon be some resistance to the pins turning in the hole and the wrench holds nearly still, while the housing and the socket turn. This operation turns the collar on to the pin until the collar makes a firm engagement with the body adjacent to it. It will be seen that when the collar moves along the pin, the socket can recede into the tubular portion 69, while the end of the pin can advance into the recess 49 in the Wrench.

After the collar has become seated against one of the bodies, the socket will cease to turn and the load imposed by rotation of the drive shaft, will be exerted mostly on the wrench. The wrench continues to exert this torque, tending to tighten the collar on the pin so as to compress the bodies together until a torque is exerted which is in excess of the shear strength of the reduced section 20 of the pin at groove 16. The Wrench engaging section of the pin then shears off. After the wrench engaging portion of the pin is sheared off, the Wrench simply spins free, and the socket can be pulled off leaving the fastener in its finally set condition.

It will be observed that the only connection with the drive motor is through chuck 58 and drive shaft 54. All other parts of this wrench are entirely independent of the motor force and there is no interconnection between them other than through the drive shaft. Therefore, all counter-rotative torque exerted on the blind fastener is entirely confined within structure which is independent of that which is held by the tool operator; that is, which is external of the tool structure. Thus, when the pin stops spinning in the hole, or the collar stops spinning relative to the plate, either of which conditions can readily occur, the other part will continue to rotate at a speed dictated by the rotational velocity of the drive shaft, which is controlled only by an oif-on switch. When the torque at which the fastener yields is reached, this torque is entirely generated by forces passed through the housing, the planetary gears, the spider, and the wrench without any reference whatever to any stationary or outside structure. Therefore, the operator does not enter into the amount of torque or the rate at which the torque is applied. Thus, the amount of torque and the manner in which it is exerted is entirely reproducible from fastener to fastener without any difierences occasioned by the tool or the operator. Furthermore, because all reactions take place within structure which is not related to the operator, there will be no shock to the operator just before the device yields, or just after it lets go. Thus, as far as the operator is concerned, this device is always a free-spinning one whose characteristics are determined entirely by the tool and are entirely independent of him.

This invention is not to be limited by the embodiment shown in the drawings and described in the description, which is given by way of example and not of limitation, but only in accordance with the scope of the appended claims.

I claim:

1. A tool for tightening a threaded fastener of the type .wherein a collar is threaded onto a threaded pin, comprising: a cage having an axis of rotation and an inner cavity, a ring gear having inwardly directed gear teeth Within said cavity attached to said cage and centered on the said axis of rotation, a wrench carrying fastener-engaging surfaces, a spider member, a central drive gear member, said members and wrench having a common axis of rotation coincident with the axis of rotation of the cage, a planetary gear journaled only by said spider, and interconnecting the drive gear and the ring gear, a drive shaft, a socket carried by said cage for rotation therewith, and collarengaging surfaces within the socket and surrounding the wrench, one of said members being attached to said wrench, and the other of said members being attached to said drive shaft, the cage, wrench, and planetary gear being freely rotatable relative to structure exterior of the tool.

2. A tool according to claim 1 in which the wrench and the socket are axially shiftable relative to each other, one of them being spring-loaded away from the drive shaft.

3. A tool for tightening a threaded fastener of the type wherein a collar is threaded onto a threaded pin, comprising: a cage having an axis of rotation and an inner cavity, a ring gear having inwardly directed gear teeth Within said cavity attached to said cage and centered on the said axis of rotation; a wrench carrying fastener-engaging surfaces; a spider affixed to said wrench, said wrench and spider having a common axis of rotation coincident with the axis of rotation of the cage; a central drive gear on said axis of rotation; a planetary gear journaled only by said spider, interconnecting the drive gear and the ring gear; a drive shaft operatively connected to said drive gear for turning the same; a socket carried by said cage for rotation therewith, and collar-engaging surfaces within the socket and surrounding the wrench, the cage, Wrench, and planetary gear being freely rotatable relative to structure exterior of the tool.

4. A tool according to claim 3 in which the wrench and the socket are axially shiftable relative to each other, one of them being spring-loaded away from the drive shaft.

References (Zited in the file of this patent UNITED STATES PATENTS 1,343,667 Evensen June 15, 1920 2,479,225 Gann Aug. 16, 1949 2,745,303 Cornelius May 15, 1956 2,760,393 Stough 2. Aug. 28, 1956 2,776,681 Hopkins Ian. 8, 1957 2,789,597 La Torre Apr. 23, 1957 2,820,382 Smith Jan. 21, 1958 2,882,773 Wing Apr. 21, 1959 

